6d1c0e5ba6
The `drain server` commands removes a server from all services and waits until all the connections for it are closed. Once the server is no longer in use, it will be set into maintenance mode and put back into the services where it was removed from.
113 lines
4.8 KiB
JavaScript
113 lines
4.8 KiB
JavaScript
/*
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* Copyright (c) 2016 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2020-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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require('./common.js')()
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function waitUntilZero(host, target, path, timeout) {
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return new Promise((resolve, reject) => {
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const interval = 2 // How often we poll the value
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var total = 0 // Estimation of how long we've been waiting
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// Using a timer will slow down the initial check but given that the idea is to drain the
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// node, it shouldn't be that problematic
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var timer = setInterval(() => {
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total += interval
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// Read and extract the value
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// Note: It is possible that the interval between requests is less than the configured 2
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// seconds since doing the request itself takes some time. This means that it's also
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// possible that parallel requests are executed which could cause problems. Upgrading to
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// a newer Node.js would allow the use of async/await which should make these sorts of
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// things easier to deal with.
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doRequest(host, target, (res) => {
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var v = _.get(res, path, -1)
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if (v <= 0 || total >= timeout) {
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// Value is zero or the timeout was hit
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clearInterval(timer)
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if (v == -1) {
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// This should never happen as long as correct versions are used
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reject('Invalid path: ' + path)
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} else if (total >= timeout) {
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reject('Drain timeout exceeded')
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} else {
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resolve()
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}
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}
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})
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.catch((err) => reject(err))
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}, 2000)
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})
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}
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exports.command = 'drain <command>'
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exports.desc = 'Drain objects'
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exports.handler = function() {}
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exports.builder = function(yargs) {
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yargs
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.group(['drain-timeout'], 'Drain options:')
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.option('drain-timeout', {
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describe: 'Timeout for the drain operation in seconds. If exceeded, the server ' +
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'is added back to all services without putting it into maintenance mode.',
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default: 90,
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type: 'number'
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})
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.command('server <server>', 'Drain a server of connections', function(yargs) {
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return yargs.epilog('This command drains the server of connections by first removing it ' +
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'from all services after which it waits until all connections are ' +
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'closed. When all connections are closed, the server is put into the ' +
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'`maintenance` state and added back to all the services where it was ' +
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'removed from. To take the server back into use, execute ' +
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'`clear server <server> maintenance`.')
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.usage('Usage: drain server <server>')
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}, function(argv) {
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maxctrl(argv, function(host) {
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var target = 'servers/' + argv.server
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var path = 'data.relationships.services.data'
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var timeout = argv['drain-timeout']
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return doRequest(host, target, (res) => {
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// Store the services, used later to add the server back into them
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var services =_.get(res, path, [])
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// Remove the relationships
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_.set(res, path, [])
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// Remove unneeded data
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delete res.data.attributes
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var addServersBack = () => {
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_.set(res, path, services)
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return doRequest(host, target, null, {method: 'PATCH', body: res})
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}
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return doRequest(host, target, null, {method: 'PATCH', body: res})
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.then(() => waitUntilZero(host, target, 'data.attributes.statistics.connections', timeout))
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.then(() => doRequest(host, target + '/set?state=maintenance', null, {method: 'PUT'}))
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.then(addServersBack, addServersBack) // Try to add the servers back even if we receive an error
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})
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})
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})
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.usage('Usage: drain <command>')
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.help()
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.command('*', 'the default command', {}, function(argv) {
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maxctrl(argv, function(host) {
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return error('Unknown command. See output of `help drain` for a list of commands.')
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})
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})
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}
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