cloudron-box/src/docker.js

'use strict';

exports = module.exports = {
    testRegistryConfig,
    setRegistryConfig,
    injectPrivateFields,
    removePrivateFields,

    ping,

    info,
    downloadImage,
    createContainer,
    startContainer,
    restartContainer,
    stopContainer,
    stopContainerByName: stopContainer,
    stopContainers,
    deleteContainer,
    deleteImage,
    deleteContainers,
    createSubcontainer,
    getContainerIdByIp,
    inspect,
    getContainerIp,
    inspectByName: inspect,
    execContainer,
    getEvents,
    memoryUsage,
    createVolume,
    removeVolume,
    clearVolume,
    update
};

const apps = require('./apps.js'),
    async = require('async'),
    assert = require('assert'),
    BoxError = require('./boxerror.js'),
    child_process = require('child_process'),
    constants = require('./constants.js'),
    debug = require('debug')('box:docker'),
    Docker = require('dockerode'),
    os = require('os'),
    path = require('path'),
    services = require('./services.js'),
    settings = require('./settings.js'),
    shell = require('./shell.js'),
    safe = require('safetydance'),
    system = require('./system.js'),
    util = require('util'),
    volumes = require('./volumes.js'),
    _ = require('underscore');

const CLEARVOLUME_CMD = path.join(__dirname, 'scripts/clearvolume.sh'),
    MKDIRVOLUME_CMD = path.join(__dirname, 'scripts/mkdirvolume.sh');

const DOCKER_SOCKET_PATH = '/var/run/docker.sock';
const gConnection = new Docker({ socketPath: DOCKER_SOCKET_PATH });

function testRegistryConfig(auth, callback) {
    assert.strictEqual(typeof auth, 'object');
    assert.strictEqual(typeof callback, 'function');

    gConnection.checkAuth(auth, function (error /*, data */) { // this returns a 500 even for auth errors
        if (error) return callback(new BoxError(BoxError.BAD_FIELD, error, { field: 'serverAddress' }));

        callback();
    });
}

function injectPrivateFields(newConfig, currentConfig) {
    if (newConfig.password === constants.SECRET_PLACEHOLDER) newConfig.password = currentConfig.password;
}

function removePrivateFields(registryConfig) {
    assert.strictEqual(typeof registryConfig, 'object');

    if (registryConfig.password) registryConfig.password = constants.SECRET_PLACEHOLDER;

    return registryConfig;
}

function setRegistryConfig(auth, callback) {
    assert.strictEqual(typeof auth, 'object');
    assert.strictEqual(typeof callback, 'function');

    const isLogin = !!auth.password;

    // currently, auth info is not stashed in the db but maybe it should for restore to work?
    const cmd = isLogin ? `docker login ${auth.serverAddress} --username ${auth.username} --password ${auth.password}` : `docker logout ${auth.serverAddress}`;

    child_process.exec(cmd, { }, function (error /*, stdout, stderr */) {
        if (error) return callback(new BoxError(BoxError.ACCESS_DENIED, error.message));

        callback();
    });
}

function ping(callback) {
    assert.strictEqual(typeof callback, 'function');

    // do not let the request linger
    const connection = new Docker({ socketPath: DOCKER_SOCKET_PATH, timeout: 1000 });

    connection.ping(function (error, result) {
        if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));
        if (Buffer.isBuffer(result) && result.toString('utf8') === 'OK') return callback(null); // sometimes it returns buffer
        if (result === 'OK') return callback(null);

        callback(new BoxError(BoxError.DOCKER_ERROR, 'Unable to ping the docker daemon'));
    });
}

function getRegistryConfig(image, callback) {
    // https://github.com/docker/distribution/blob/release/2.7/reference/normalize.go#L62
    const parts = image.split('/');
    if (parts.length === 1 || (parts[0].match(/[.:]/) === null)) return callback(null, null); // public docker registry

    settings.getRegistryConfig(function (error, registryConfig) {
        if (error) return callback(error);

        // https://github.com/apocas/dockerode#pull-from-private-repos
        const auth = {
            username: registryConfig.username,
            password: registryConfig.password,
            auth: registryConfig.auth || '', // the auth token at login time
            email: registryConfig.email || '',
            serveraddress: registryConfig.serverAddress
        };

        callback(null, auth);
    });
}

function pullImage(manifest, callback) {
    getRegistryConfig(manifest.dockerImage, function (error, authConfig) {
        if (error) return callback(error);

        debug(`pullImage: will pull ${manifest.dockerImage}. auth: ${authConfig ? 'yes' : 'no'}`);

        gConnection.pull(manifest.dockerImage, { authconfig: authConfig }, function (error, stream) {
            if (error && error.statusCode === 404) return callback(new BoxError(BoxError.NOT_FOUND, `Unable to pull image ${manifest.dockerImage}. message: ${error.message} statusCode: ${error.statusCode}`));
            if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, `Unable to pull image ${manifest.dockerImage}. Please check the network or if the image needs authentication. statusCode: ${error.statusCode}`));

            // https://github.com/dotcloud/docker/issues/1074 says each status message
            // is emitted as a chunk
            stream.on('data', function (chunk) {
                var data = safe.JSON.parse(chunk) || { };
                debug('pullImage: %j', data);

                // The data.status here is useless because this is per layer as opposed to per image
                if (!data.status && data.error) {
                    debug('pullImage error %s: %s', manifest.dockerImage, data.errorDetail.message);
                }
            });

            stream.on('end', function () {
                debug('downloaded image %s', manifest.dockerImage);

                callback(null);
            });

            stream.on('error', function (error) {
                debug('error pulling image %s: %j', manifest.dockerImage, error);

                callback(new BoxError(BoxError.DOCKER_ERROR, error.message));
            });
        });
    });
}

function downloadImage(manifest, callback) {
    assert.strictEqual(typeof manifest, 'object');
    assert.strictEqual(typeof callback, 'function');

    debug('downloadImage %s', manifest.dockerImage);

    const image = gConnection.getImage(manifest.dockerImage);

    image.inspect(function (error, result) {
        if (!error && result) return callback(null); // image is already present locally

        let attempt = 1;

        async.retry({ times: 10, interval: 5000, errorFilter: e => e.reason !== BoxError.NOT_FOUND }, function (retryCallback) {
            debug('Downloading image %s. attempt: %s', manifest.dockerImage, attempt++);

            pullImage(manifest, retryCallback);
        }, callback);
    });
}

function getBinds(app, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof callback, 'function');

    if (app.mounts.length === 0) return callback(null);

    let binds = [];

    volumes.list(function (error, result) {
        if (error) return callback(error);
        let volumesById = {};
        result.forEach(r => volumesById[r.id] = r);

        for (const mount of app.mounts) {
            const volume = volumesById[mount.volumeId];
            binds.push(`${volume.hostPath}:/media/${volume.name}:${mount.readOnly ? 'ro' : 'rw'}`);
        }

        callback(null, binds);
    });
}

function getLowerUpIp() { // see getifaddrs and IFF_LOWER_UP and netdevice
    const ni = os.networkInterfaces(); // { lo: [], eth0: [] }
    for (const iname of Object.keys(ni)) {
        if (iname === 'lo') continue;
        for (const address of ni[iname]) {
            if (!address.internal && address.family === 'IPv4') return address.address;
        }
    }

    return null;
}

function createSubcontainer(app, name, cmd, options, callback) {
    assert.strictEqual(typeof app, 'object');
    assert.strictEqual(typeof name, 'string');
    assert(!cmd || util.isArray(cmd));
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof callback, 'function');

    let isAppContainer = !cmd; // non app-containers are like scheduler

    var manifest = app.manifest;
    var exposedPorts = {}, dockerPortBindings = { };
    var domain = app.fqdn;

    const envPrefix = manifest.manifestVersion <= 1 ? '' : 'CLOUDRON_';

    let stdEnv = [
        'CLOUDRON=1',
        'CLOUDRON_PROXY_IP=172.18.0.1',
        `CLOUDRON_APP_HOSTNAME=${app.id}`,
        `${envPrefix}WEBADMIN_ORIGIN=${settings.adminOrigin()}`,
        `${envPrefix}API_ORIGIN=${settings.adminOrigin()}`,
        `${envPrefix}APP_ORIGIN=https://${domain}`,
        `${envPrefix}APP_DOMAIN=${domain}`
    ];

    var portEnv = [];
    for (let portName in app.portBindings) {
        const hostPort = app.portBindings[portName];
        const portType = (manifest.tcpPorts && portName in manifest.tcpPorts) ? 'tcp' : 'udp';
        const ports = portType == 'tcp' ? manifest.tcpPorts : manifest.udpPorts;

        var containerPort = ports[portName].containerPort || hostPort;

        // docker portBindings requires ports to be exposed
        exposedPorts[`${containerPort}/${portType}`] = {};
        portEnv.push(`${portName}=${hostPort}`);

        const hostIp = hostPort === 53 ? getLowerUpIp() : '0.0.0.0'; // port 53 is special because it is possibly taken by systemd-resolved
        dockerPortBindings[`${containerPort}/${portType}`] = [ { HostIp: hostIp, HostPort: hostPort + '' } ];
    }

    let appEnv = [];
    Object.keys(app.env).forEach(function (name) { appEnv.push(`${name}=${app.env[name]}`); });

    let memoryLimit = apps.getMemoryLimit(app);

    // give scheduler tasks twice the memory limit since background jobs take more memory
    // if required, we can make this a manifest and runtime argument later
    if (!isAppContainer) memoryLimit *= 2;

    services.getEnvironment(app, function (error, addonEnv) {
        if (error) return callback(error);

        getBinds(app, function (error, binds) {
            if (error) return callback(error);

            let containerOptions = {
                name: name, // for referencing containers
                Tty: isAppContainer,
                Image: app.manifest.dockerImage,
                Cmd: (isAppContainer && app.debugMode && app.debugMode.cmd) ? app.debugMode.cmd : cmd,
                Env: stdEnv.concat(addonEnv).concat(portEnv).concat(appEnv),
                ExposedPorts: isAppContainer ? exposedPorts : { },
                Volumes: { // see also ReadonlyRootfs
                    '/tmp': {},
                    '/run': {}
                },
                Labels: {
                    'fqdn': app.fqdn,
                    'appId': app.id,
                    'isSubcontainer': String(!isAppContainer),
                    'isCloudronManaged': String(true)
                },
                HostConfig: {
                    Mounts: services.getMountsSync(app, app.manifest.addons),
                    Binds: binds, // ideally, we have to use 'Mounts' but we have to create volumes then
                    LogConfig: {
                        Type: 'syslog',
                        Config: {
                            'tag': app.id,
                            'syslog-address': 'udp://127.0.0.1:2514', // see apps.js:validatePortBindings()
                            'syslog-format': 'rfc5424'
                        }
                    },
                    Memory: system.getMemoryAllocation(memoryLimit),
                    MemorySwap: memoryLimit, // Memory + Swap
                    PortBindings: isAppContainer ? dockerPortBindings : { },
                    PublishAllPorts: false,
                    ReadonlyRootfs: app.debugMode ? !!app.debugMode.readonlyRootfs : true,
                    RestartPolicy: {
                        'Name': isAppContainer ? 'unless-stopped' : 'no',
                        'MaximumRetryCount': 0
                    },
                    CpuShares: app.cpuShares,
                    VolumesFrom: isAppContainer ? null : [ app.containerId + ':rw' ],
                    SecurityOpt: [ 'apparmor=docker-cloudron-app' ],
                    CapAdd: [],
                    CapDrop: []
                }
            };

            // do no set hostname of containers to location as it might conflict with addons names. for example, an app installed in mail
            // location may not reach mail container anymore by DNS. We cannot set hostname to fqdn either as that sets up the dns
            // name to look up the internal docker ip. this makes curl from within container fail
            // Note that Hostname has no effect on DNS. We have to use the --net-alias for dns.
            // Hostname cannot be set with container NetworkMode. Subcontainers run is the network space of the app container
            // This is done to prevent lots of up/down events and iptables locking
            if (isAppContainer) {
                containerOptions.Hostname = app.id;
                containerOptions.HostConfig.NetworkMode = 'cloudron'; // user defined bridge network
                containerOptions.HostConfig.Dns = ['172.18.0.1']; // use internal dns
                containerOptions.HostConfig.DnsSearch = ['.']; // use internal dns

                containerOptions.NetworkingConfig = {
                    EndpointsConfig: {
                        cloudron: {
                            IPAMConfig: {
                                IPv4Address: app.containerIp
                            },
                            Aliases: [ name ] // adds hostname entry with container name
                        }
                    }
                };
            } else {
                containerOptions.HostConfig.NetworkMode = `container:${app.containerId}`; // scheduler containers must have same IP as app for various addon auth
            }

            var capabilities = manifest.capabilities || [];

            // https://docs-stage.docker.com/engine/reference/run/#runtime-privilege-and-linux-capabilities
            if (capabilities.includes('net_admin')) containerOptions.HostConfig.CapAdd.push('NET_ADMIN', 'NET_RAW');
            if (capabilities.includes('mlock')) containerOptions.HostConfig.CapAdd.push('IPC_LOCK'); // mlock prevents swapping
            if (!capabilities.includes('ping')) containerOptions.HostConfig.CapDrop.push('NET_RAW'); // NET_RAW is included by default by Docker

            if (capabilities.includes('vaapi') && safe.fs.existsSync('/dev/dri')) {
                containerOptions.HostConfig.Devices = [
                    { PathOnHost: '/dev/dri', PathInContainer: '/dev/dri', CgroupPermissions: 'rwm' }
                ];
            }

            containerOptions = _.extend(containerOptions, options);

            gConnection.createContainer(containerOptions, function (error, container) {
                if (error && error.statusCode === 409) return callback(new BoxError(BoxError.ALREADY_EXISTS, error));
                if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

                callback(null, container);
            });
        });
    });
}

function createContainer(app, callback) {
    createSubcontainer(app, app.id /* name */, null /* cmd */, { } /* options */, callback);
}

function startContainer(containerId, callback) {
    assert.strictEqual(typeof containerId, 'string');
    assert.strictEqual(typeof callback, 'function');

    var container = gConnection.getContainer(containerId);

    container.start(function (error) {
        if (error && error.statusCode === 404) return callback(new BoxError(BoxError.NOT_FOUND));
        if (error && error.statusCode === 400) return callback(new BoxError(BoxError.BAD_FIELD, error)); // e.g start.sh is not executable
        if (error && error.statusCode !== 304) return callback(new BoxError(BoxError.DOCKER_ERROR, error)); // 304 means already started

        return callback(null);
    });
}

function restartContainer(containerId, callback) {
    assert.strictEqual(typeof containerId, 'string');
    assert.strictEqual(typeof callback, 'function');

    var container = gConnection.getContainer(containerId);

    container.restart(function (error) {
        if (error && error.statusCode === 404) return callback(new BoxError(BoxError.NOT_FOUND));
        if (error && error.statusCode === 400) return callback(new BoxError(BoxError.BAD_FIELD, error)); // e.g start.sh is not executable
        if (error && error.statusCode !== 204) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

        return callback(null);
    });
}

function stopContainer(containerId, callback) {
    assert(!containerId || typeof containerId === 'string');
    assert.strictEqual(typeof callback, 'function');

    if (!containerId) {
        debug('No previous container to stop');
        return callback();
    }

    var container = gConnection.getContainer(containerId);

    var options = {
        t: 10 // wait for 10 seconds before killing it
    };

    container.stop(options, function (error) {
        if (error && (error.statusCode !== 304 && error.statusCode !== 404)) return callback(new BoxError(BoxError.DOCKER_ERROR, 'Error stopping container:' + error.message));

        container.wait(function (error/*, data */) {
            if (error && (error.statusCode !== 304 && error.statusCode !== 404)) return callback(new BoxError(BoxError.DOCKER_ERROR, 'Error waiting on container:' + error.message));

            return callback(null);
        });
    });
}

function deleteContainer(containerId, callback) { // id can also be name
    assert(!containerId || typeof containerId === 'string');
    assert.strictEqual(typeof callback, 'function');

    if (containerId === null) return callback(null);

    var container = gConnection.getContainer(containerId);

    var removeOptions = {
        force: true, // kill container if it's running
        v: true // removes volumes associated with the container (but not host mounts)
    };

    container.remove(removeOptions, function (error) {
        if (error && error.statusCode === 404) return callback(null);

        if (error) {
            debug('Error removing container %s : %j', containerId, error);
            return callback(new BoxError(BoxError.DOCKER_ERROR, error));
        }

        callback(null);
    });
}

function deleteContainers(appId, options, callback) {
    assert.strictEqual(typeof appId, 'string');
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof callback, 'function');

    let labels = [ 'appId=' + appId ];
    if (options.managedOnly) labels.push('isCloudronManaged=true');

    gConnection.listContainers({ all: 1, filters: JSON.stringify({ label: labels }) }, function (error, containers) {
        if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

        async.eachSeries(containers, function (container, iteratorDone) {
            deleteContainer(container.Id, iteratorDone);
        }, callback);
    });
}

function stopContainers(appId, callback) {
    assert.strictEqual(typeof appId, 'string');
    assert.strictEqual(typeof callback, 'function');

    gConnection.listContainers({ all: 1, filters: JSON.stringify({ label: [ 'appId=' + appId ] }) }, function (error, containers) {
        if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

        async.eachSeries(containers, function (container, iteratorDone) {
            stopContainer(container.Id, iteratorDone);
        }, callback);
    });
}

function deleteImage(manifest, callback) {
    assert(!manifest || typeof manifest === 'object');
    assert.strictEqual(typeof callback, 'function');

    var dockerImage = manifest ? manifest.dockerImage : null;
    if (!dockerImage) return callback(null);

    var removeOptions = {
        force: false, // might be shared with another instance of this app
        noprune: false // delete untagged parents
    };

    // registry v1 used to pull down all *tags*. this meant that deleting image by tag was not enough (since that
    // just removes the tag). we used to remove the image by id. this is not required anymore because aliases are
    // not created anymore after https://github.com/docker/docker/pull/10571
    gConnection.getImage(dockerImage).remove(removeOptions, function (error) {
        if (error && error.statusCode === 400) return callback(null); // invalid image format. this can happen if user installed with a bad --docker-image
        if (error && error.statusCode === 404) return callback(null); // not found
        if (error && error.statusCode === 409) return callback(null); // another container using the image

        if (error) {
            debug('Error removing image %s : %j', dockerImage, error);
            return callback(new BoxError(BoxError.DOCKER_ERROR, error));
        }

        callback(null);
    });
}

function getContainerIdByIp(ip, callback) {
    assert.strictEqual(typeof ip, 'string');
    assert.strictEqual(typeof callback, 'function');

    gConnection.getNetwork('cloudron').inspect(function (error, bridge) {
        if (error && error.statusCode === 404) return callback(new BoxError(BoxError.DOCKER_ERROR, 'Unable to find the cloudron network'));
        if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

        var containerId;
        for (var id in bridge.Containers) {
            if (bridge.Containers[id].IPv4Address.indexOf(ip + '/16') === 0) {
                containerId = id;
                break;
            }
        }
        if (!containerId) return callback(new BoxError(BoxError.DOCKER_ERROR, 'No container with that ip'));

        callback(null, containerId);
    });
}

function inspect(containerId, callback) {
    assert.strictEqual(typeof containerId, 'string');
    assert.strictEqual(typeof callback, 'function');

    var container = gConnection.getContainer(containerId);

    container.inspect(function (error, result) {
        if (error && error.statusCode === 404) return callback(new BoxError(BoxError.NOT_FOUND, `Unable to find container ${containerId}`));
        if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

        callback(null, result);
    });
}

function getContainerIp(containerId, callback) {
    assert.strictEqual(typeof containerId, 'string');
    assert.strictEqual(typeof callback, 'function');

    if (constants.TEST) return callback(null, '127.0.5.5');

    inspect(containerId, function (error, result) {
        if (error) return callback(error);

        const ip = safe.query(result, 'NetworkSettings.Networks.cloudron.IPAddress', null);
        if (!ip) return callback(new BoxError(BoxError.DOCKER_ERROR, 'Error getting container IP'));

        callback(null, ip);
    });
}

function execContainer(containerId, options, callback) {
    assert.strictEqual(typeof containerId, 'string');
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof callback, 'function');

    var container = gConnection.getContainer(containerId);

    container.exec(options.execOptions, function (error, exec) {
        if (error && error.statusCode === 409) return callback(new BoxError(BoxError.BAD_STATE, error.message)); // container restarting/not running
        if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

        exec.start(options.startOptions, function(error, stream /* in hijacked mode, this is a net.socket */) {
            if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

            if (options.rows && options.columns) {
                // there is a race where resizing too early results in a 404 "no such exec"
                // https://git.cloudron.io/cloudron/box/issues/549
                setTimeout(function () {
                    exec.resize({ h: options.rows, w: options.columns }, function (error) { if (error) debug('Error resizing console', error); });
                }, 2000);
            }

            callback(null, stream);
        });
    });
}

function getEvents(options, callback) {
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof callback, 'function');

    gConnection.getEvents(options, function (error, stream) {
        if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

        callback(null, stream);
    });
}

function memoryUsage(containerId, callback) {
    assert.strictEqual(typeof containerId, 'string');
    assert.strictEqual(typeof callback, 'function');

    var container = gConnection.getContainer(containerId);

    container.stats({ stream: false }, function (error, result) {
        if (error && error.statusCode === 404) return callback(new BoxError(BoxError.NOT_FOUND));
        if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

        callback(null, result);
    });
}

function createVolume(name, volumeDataDir, labels, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof volumeDataDir, 'string');
    assert.strictEqual(typeof labels, 'object');
    assert.strictEqual(typeof callback, 'function');

    const volumeOptions = {
        Name: name,
        Driver: 'local',
        DriverOpts: { // https://github.com/moby/moby/issues/19990#issuecomment-248955005
            type: 'none',
            device: volumeDataDir,
            o: 'bind'
        },
        Labels: labels
    };

    // requires sudo because the path can be outside appsdata
    shell.sudo('createVolume', [ MKDIRVOLUME_CMD, volumeDataDir ], {}, function (error) {
        if (error) return callback(new BoxError(BoxError.FS_ERROR, `Error creating app data dir: ${error.message}`));

        gConnection.createVolume(volumeOptions, function (error) {
            if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

            callback();
        });
    });
}

function clearVolume(name, options, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof options, 'object');
    assert.strictEqual(typeof callback, 'function');

    let volume = gConnection.getVolume(name);
    volume.inspect(function (error, v) {
        if (error && error.statusCode === 404) return callback();
        if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, error));

        const volumeDataDir = v.Options.device;
        shell.sudo('clearVolume', [ CLEARVOLUME_CMD, options.removeDirectory ? 'rmdir' : 'clear', volumeDataDir ], {}, function (error) {
            if (error) return callback(new BoxError(BoxError.FS_ERROR, error));

            callback();
        });
    });
}

// this only removes the volume and not the data
function removeVolume(name, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof callback, 'function');

    let volume = gConnection.getVolume(name);
    volume.remove(function (error) {
        if (error && error.statusCode !== 404) return callback(new BoxError(BoxError.DOCKER_ERROR, `removeVolume: Error removing volume: ${error.message}`));

        callback();
    });
}

function info(callback) {
    assert.strictEqual(typeof callback, 'function');

    gConnection.info(function (error, result) {
        if (error) return callback(new BoxError(BoxError.DOCKER_ERROR, 'Error connecting to docker'));

        callback(null, result);
    });
}

function update(name, memory, memorySwap, callback) {
    assert.strictEqual(typeof name, 'string');
    assert.strictEqual(typeof memory, 'number');
    assert.strictEqual(typeof memorySwap, 'number');
    assert.strictEqual(typeof callback, 'function');

    const args = `update --memory ${memory} --memory-swap ${memorySwap} ${name}`.split(' ');
    // scale back db containers, if possible. this is retried because updating memory constraints can fail
    // with failed to write to memory.memsw.limit_in_bytes: write /sys/fs/cgroup/memory/docker/xx/memory.memsw.limit_in_bytes: device or resource busy
    async.retry({ times: 10, interval: 60 * 1000 }, function (retryCallback) {
        shell.spawn(`update(${name})`, '/usr/bin/docker', args, { }, retryCallback);
    }, callback);
}