https://github.com/fentas/docker-mongo-replset
A container that provides discovery for mongodb replica sets via the rancher API
https://github.com/fentas/docker-mongo-replset
Last synced: 2 months ago
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A container that provides discovery for mongodb replica sets via the rancher API
- Host: GitHub
- URL: https://github.com/fentas/docker-mongo-replset
- Owner: fentas
- Created: 2015-08-01T18:06:18.000Z (almost 10 years ago)
- Default Branch: master
- Last Pushed: 2015-11-13T13:08:10.000Z (over 9 years ago)
- Last Synced: 2023-08-17T07:11:43.528Z (almost 2 years ago)
- Language: Shell
- Homepage:
- Size: 91.8 KB
- Stars: 4
- Watchers: 2
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
Mongo replica set watcher (adjusted for Rancher)
---
*Little* bash script, wrapped into a docker container, to be ground control
for any mongo replica set within [Rancher](http://rancher.com/).
Environment
---
* `MONGO_REPLSET` ..name of replica set
> "rs0"
* `PORT` ..port for mongo instances
> 27017
* `VERBOSE` ..verbose level according to [https://en.wikipedia.org/wiki/Syslog#Severity_level](https://en.wikipedia.org/wiki/Syslog#Severity_level)
> 6
* `META_URL` ..rancher [meta data](http://docs.rancher.com/rancher/metadata-service/) url
> "http://rancher-metadata/2015-07-25"
* `SERVICE` ..(dns) service name
> "mongo-replset"
* `HOST_LABEL` ..[host label](http://docs.rancher.com/rancher/rancher-ui/infrastructure/hosts/custom/#host-labels) for mongo instance preference
> "mongo"
* `INTERVAL` ..instance lookup interval (in secs)
> 30
* `MAINTENANCE` ..if mongo instance preferences are of when to recondig replica set. (as [cron tab expression](https://github.com/fentas/cronexpr))
> "@daily"
* `AUTHENTICATION` ..needs clusterManager admin role. (as "<< user >>**:**<< password >>")
> ""
Behavior
---
Checks every mongod instance behind a service and compares it to its
host label (as means of configuration).
This can be `primary`, `secondary`, `arbiter` and `hidden`.
If the replica set is not initialized yet, it will force `reconfig` accordingly to
the given host labels. (e.g. if `arbiter` **priority** of this member will be **0** and
*arbiterOnly* **true**)
If it is already initialized and there are any missfits, a `reconfig` will be
triggered on the specified `MAINTINACE` time.
Also it has an eye on newcomers and stales. Meaning it will *add* or *remove*
this instances accordingly. **Notice** if a `hidden` instance is newly added it will
be **not** hidden until a `reconfig`.
Workflow
---
First consider to create a config file for mongod on each host.
> Here one example for **PRIMARY**, **SECONDARY**, **ARBITER** construct.
> (`/data/mongo/mongod.yml`)
**If you expose port 27017 you need at least 3 different hosts.**
##### PRIMARY
```yml
storage:
dbPath: "/data/db/_/"
directoryPerDB: true
journal:
enabled: true
net:
bindIp: 127.0.0.1
port: 27017
security:
# same key on every host
keyFile: "/data/db/key/mongo-rs0.key"
#TODO: first create admin user
#authorization: "enabled"
replication:
# usually takes 5% of free space. Set this depending on free space.
oplogSizeMB: 10240
replSetName: "rs0"
```
##### SECONDARY
```yml
# secondary
storage:
dbPath: "/data/db/_/"
directoryPerDB: true
journal:
enabled: true
net:
bindIp: 127.0.0.1
port: 27017
security:
keyFile: "/data/db/key/mongo-rs0.key"
#TODO: first create admin user
#authorization: "enabled"
replication:
# usually takes 5% of free space.
oplogSizeMB: 10240
replSetName: "rs0"
```
##### ARBITER
```yml
# arbiter
storage:
dbPath: "/data/db/_/"
directoryPerDB: true
journal:
enabled: false
mmapv1:
smallFiles: true
net:
bindIp: 127.0.0.1
port: 27017
security:
keyFile: "/data/db/key/mongo-rs0.key"
#TODO: first create admin user
# authorization: "enabled"
replication:
# arbiter do not have any data. Prevent space allocation.
oplogSizeMB: 8
replSetName: "rs0"
```
Then add your hosts to Rancher. Each with a label named `mongo`. As value for
this label you specify the role of of the mongo instance. You can add host
labels on first time registration over cli or using `rancher/server` ui.
[See here for more](http://docs.rancher.com/rancher/rancher-ui/infrastructure/hosts/custom/#host-labels)
Due to a not implemented feature [see](https://github.com/rancher/rancher/issues/2601) also
add host label `mongo-replset=1`.
Now start your mongod instances, easily on specifying `mongo` key as schedule
requirement.
[See here for more](http://docs.rancher.com/rancher/concepts/scheduling/)
> Here's an example.
##### rancher-compose.yml
```yml
mongo-replSet-rs0:
scale: 3
```
##### docker-compose.yml
```yml
mongo-replSet-rs0:
container_name: mongo-replSet-rs0
image: mongo:3.0
command: mongod --config /mongod.yml
stdin_open: true
tty: true
restart: always
ports:
- "27017:27017"
volumes:
- /data/mongo/mongod.yml:/mongod.yml:ro
- /data/mongo-rs0.key:/data/db/key/mongo-rs0.key
# if you want to host mongodb data
- /data/db/:/data/db/_/:rw
labels:
#Not possible yet https://github.com/rancher/rancher/issues/2601
#io.rancher.scheduler.affinity:host_label: mongo in (primary, secondary, arbiter, hidden)
#Workaround
io.rancher.scheduler.affinity:host_label: mongo-replset=1
health_check:
port: 27017
interval: 2000
healthy_threshold: 2
unhealthy_threshold: 3
response_timeout: 2000
```
After that there should be 3 mongod instances running on the specified hosts.
This leaves you with the last step, starting this docker container.
> Maybe like this.
##### rancher-compose.yml
```yml
mongo-replSet-watch:
scale: 1
```
##### docker-compose.yml
```yml
mongo-replSet-watch:
image: fentas/mongo-replset:latest
stdin_open: true
tty: true
restart: always
links:
- mongo-replSet-rs0:mongo-replset
environment:
SERVICE: "mongo-replSet"
MONGO_REPLSET: "rs0"
AUTHENTICATION: ":"
labels:
# do this if you have more then 3 hosts (for this example)
#io.rancher.scheduler.affinity:host_label_ne: mongo in (primary, secondary, arbiter, hidden)
io.rancher.scheduler.affinity:host_label_ne: mongo-replset=1
io.rancher.container.pull_image: always
```
This shoud be it.
TODOs
---
* Somehow writing test case(?)
* Work in progress. Any ideas?
Light reading
---
* [http://docs.rancher.com/rancher/](http://docs.rancher.com/rancher/)
* [https://docs.mongodb.org/manual/core/replica-set-members/](https://docs.mongodb.org/manual/core/replica-set-members/)
* [https://docs.mongodb.org/manual/reference/method/rs.reconfig/#rs.reconfig](https://docs.mongodb.org/manual/reference/method/rs.reconfig/#rs.reconfig)
* [https://docs.mongodb.org/manual/tutorial/enable-internal-authentication/](https://docs.mongodb.org/manual/tutorial/enable-internal-authentication/)
Contributing
---
Alway welcome. Feel free to create issues or pull requests.
Originally forked from [https://github.com/azenk/mongodb-kubernetes](https://github.com/azenk/mongodb-kubernetes)
Licence
---
AGPLv3 - [http://choosealicense.com/licenses/agpl-3.0/](http://choosealicense.com/licenses/agpl-3.0/)