This is how I setup a mongodb and a backend app using docker-compose. As I am running an old mongodb instance on port 27017, I have to use another port. So this is how I setup for port 27018.
Mongodb is running and I can connect using mongosh.
version: '3.5'
services:
mongo:
container_name: mongo
image: mongo:6.0.3
restart: always
ports:
- "27018:27017"
volumes:
- /opt/mongodb/data:/data/db
api:
container_name: api
image: custom-api:latest
restart: always
ports:
- "3100:3100"
environment:
- DB_HOST=mongo:27018
The backend application (nestJS) tries to connect to the DB:
const host = process.env.DB_HOST
const mongo = 'mongodb://' + host
const options = {}
const client = new MongoClient(mongo, options)
try {
await client.connect()
return client.db(database)
} catch (error) {
console.error(error)
}
But running the backend gives me a connection error:
MongoServerSelectionError: connect ECONNREFUSED 172.18.0.21:27018
at Timeout._onTimeout (/usr/src/app/node_modules/mongodb/lib/sdam/topology.js:292:38)
at listOnTimeout (node:internal/timers:559:17)
at processTimers (node:internal/timers:502:7) {
reason: TopologyDescription {
type: 'Unknown',
servers: Map(1) { 'mongo:27018' => [ServerDescription] },
stale: false,
compatible: true,
heartbeatFrequencyMS: 10000,
localThresholdMS: 15,
setName: null,
maxElectionId: null,
maxSetVersion: null,
commonWireVersion: 0,
logicalSessionTimeoutMinutes: null
},
code: undefined,
[Symbol(errorLabels)]: Set(0) {}
}
I checked the mongo container and as far as can see, it is running at port 27018 and the IP address is 172.18.0.21
$ docker inspect mongo
[
{
"Id": "8f9a6d2c36a106edbcfd84ee4bc8f3c72ce1ee13f65dc59d4f593085bb1f72f1",
"Created": "2023-04-13T06:25:48.388105401Z",
"Path": "docker-entrypoint.sh",
"Args": [
"mongod"
],
"State": {
"Status": "running",
"Running": true,
"Paused": false,
"Restarting": false,
"OOMKilled": false,
"Dead": false,
"Pid": 31483,
"ExitCode": 0,
"Error": "",
"StartedAt": "2023-04-13T06:25:49.375455874Z",
"FinishedAt": "0001-01-01T00:00:00Z"
},
"Image": "sha256:0850fead9327a6d88722c27116309022d78e9daf526b407a88de09762c32e620",
"ResolvConfPath": "/var/lib/docker/containers/8f9a6d2c36a106edbcfd84ee4bc8f3c72ce1ee13f65dc59d4f593085bb1f72f1/resolv.conf",
"HostnamePath": "/var/lib/docker/containers/8f9a6d2c36a106edbcfd84ee4bc8f3c72ce1ee13f65dc59d4f593085bb1f72f1/hostname",
"HostsPath": "/var/lib/docker/containers/8f9a6d2c36a106edbcfd84ee4bc8f3c72ce1ee13f65dc59d4f593085bb1f72f1/hosts",
"LogPath": "/var/lib/docker/containers/8f9a6d2c36a106edbcfd84ee4bc8f3c72ce1ee13f65dc59d4f593085bb1f72f1/8f9a6d2c36a106edbcfd84ee4bc8f3c72ce1ee13f65dc59d4f593085bb1f72f1-json.log",
"Name": "/mongo",
"RestartCount": 0,
"Driver": "overlay2",
"Platform": "linux",
"MountLabel": "",
"ProcessLabel": "",
"AppArmorProfile": "docker-default",
"ExecIDs": null,
"HostConfig": {
"Binds": [
"/opt/mongodb/data:/data/db:rw"
],
"ContainerIDFile": "",
"NetworkMode": "root_default",
"PortBindings": {
"27017/tcp": [
{
"HostIp": "",
"HostPort": "27018"
}
]
},
"RestartPolicy": {
"Name": "always",
"MaximumRetryCount": 0
},
"AutoRemove": false,
"VolumeDriver": "",
"VolumesFrom": [],
"CapAdd": null,
"CapDrop": null,
"Dns": null,
"DnsOptions": null,
"DnsSearch": null,
"ExtraHosts": null,
"GroupAdd": null,
"IpcMode": "shareable",
"Cgroup": "",
"Links": null,
"OomScoreAdj": 0,
"PidMode": "",
"Privileged": false,
"PublishAllPorts": false,
"ReadonlyRootfs": false,
"SecurityOpt": null,
"UTSMode": "",
"UsernsMode": "",
"ShmSize": 67108864,
"Runtime": "runc",
"ConsoleSize": [
0,
0
],
"Isolation": "",
"CpuShares": 0,
"Memory": 0,
"NanoCpus": 0,
"CgroupParent": "",
"BlkioWeight": 0,
"BlkioWeightDevice": null,
"BlkioDeviceReadBps": null,
"BlkioDeviceWriteBps": null,
"BlkioDeviceReadIOps": null,
"BlkioDeviceWriteIOps": null,
"CpuPeriod": 0,
"CpuQuota": 0,
"CpuRealtimePeriod": 0,
"CpuRealtimeRuntime": 0,
"CpusetCpus": "",
"CpusetMems": "",
"Devices": null,
"DeviceCgroupRules": null,
"DiskQuota": 0,
"KernelMemory": 0,
"MemoryReservation": 0,
"MemorySwap": 0,
"MemorySwappiness": null,
"OomKillDisable": false,
"PidsLimit": 0,
"Ulimits": null,
"CpuCount": 0,
"CpuPercent": 0,
"IOMaximumIOps": 0,
"IOMaximumBandwidth": 0,
"MaskedPaths": [
"/proc/acpi",
"/proc/kcore",
"/proc/keys",
"/proc/latency_stats",
"/proc/timer_list",
"/proc/timer_stats",
"/proc/sched_debug",
"/proc/scsi",
"/sys/firmware"
],
"ReadonlyPaths": [
"/proc/asound",
"/proc/bus",
"/proc/fs",
"/proc/irq",
"/proc/sys",
"/proc/sysrq-trigger"
]
},
"GraphDriver": {
"Data": {
"LowerDir": "/var/lib/docker/overlay2/3c94b17a3042e1ddb44e3aae5738e26c6a486c60fa827210b9c231d099c49ba3-init/diff:/var/lib/docker/overlay2/6f4fe3c9f0ebebdf05be4238d470f4e1cf47e1dcd951827f598dfefceb83f083/diff:/var/lib/docker/overlay2/b466d85cf8ecc60e7b9d843252f7a3b93e8bd42648a9293fbd21de554475293c/diff:/var/lib/docker/overlay2/5efe3f538b14b3cd7e03bfa20b47e781f8ae23585d7534620086a3426b60d1fd/diff:/var/lib/docker/overlay2/00b32be3ac44afe3c34d11a5cae80f32a0ad042a15b7d8a9b9ea3b2ef2f912d0/diff:/var/lib/docker/overlay2/68ef703e86c29ba143e94c68bcb336ca448dfb6671c4def38fcf0fd405f39cd3/diff:/var/lib/docker/overlay2/f99e7bee906d1f6ac333d704eb409ad80b5a1800f002bb604c77eab880b4d6e7/diff:/var/lib/docker/overlay2/a953e99bfbe3db3d27fbf14181309e0883ded46509a45753d7238dd3e1bcef16/diff:/var/lib/docker/overlay2/a91c55b0aa1abb4959d98ac06ec579b1193e32715d93acf3057a877cad9ee13e/diff:/var/lib/docker/overlay2/090e8dd5fd41f1676d731f7421b0878019ff30e7653059f72143ab7af156452c/diff",
"MergedDir": "/var/lib/docker/overlay2/3c94b17a3042e1ddb44e3aae5738e26c6a486c60fa827210b9c231d099c49ba3/merged",
"UpperDir": "/var/lib/docker/overlay2/3c94b17a3042e1ddb44e3aae5738e26c6a486c60fa827210b9c231d099c49ba3/diff",
"WorkDir": "/var/lib/docker/overlay2/3c94b17a3042e1ddb44e3aae5738e26c6a486c60fa827210b9c231d099c49ba3/work"
},
"Name": "overlay2"
},
"Mounts": [
{
"Type": "bind",
"Source": "/opt/mongodb/data",
"Destination": "/data/db",
"Mode": "rw",
"RW": true,
"Propagation": "rprivate"
},
{
"Type": "volume",
"Name": "ac914c3fb835b5c7028b58825558fc109c94e30b13938548bbe520ba736adbc0",
"Source": "/var/lib/docker/volumes/ac914c3fb835b5c7028b58825558fc109c94e30b13938548bbe520ba736adbc0/_data",
"Destination": "/data/configdb",
"Driver": "local",
"Mode": "",
"RW": true,
"Propagation": ""
}
],
"Config": {
"Hostname": "8f9a6d2c36a1",
"Domainname": "",
"User": "",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"ExposedPorts": {
"27017/tcp": {}
},
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
"GOSU_VERSION=1.12",
"JSYAML_VERSION=3.13.1",
"MONGO_PACKAGE=mongodb-org",
"MONGO_REPO=repo.mongodb.org",
"MONGO_MAJOR=6.0",
"MONGO_VERSION=6.0.3",
"HOME=/data/db"
],
"Cmd": [
"mongod"
],
"Image": "mongo:6.0.3",
"Volumes": {
"/data/configdb": {},
"/data/db": {}
},
"WorkingDir": "",
"Entrypoint": [
"docker-entrypoint.sh"
],
"OnBuild": null,
"Labels": {
"com.docker.compose.config-hash": "1bb0f4e8831b78bb570c3e7231260fc01cedafaedf4a8eb29808ce3c1590d21e",
"com.docker.compose.container-number": "1",
"com.docker.compose.oneoff": "False",
"com.docker.compose.project": "root",
"com.docker.compose.service": "mongo",
"com.docker.compose.version": "1.22.0"
}
},
"NetworkSettings": {
"Bridge": "",
"SandboxID": "80b5cd3f3b8cfed3fe015e886113ba4542962190a4b7ae05029f778d3ec579c7",
"HairpinMode": false,
"LinkLocalIPv6Address": "",
"LinkLocalIPv6PrefixLen": 0,
"Ports": {
"27017/tcp": [
{
"HostIp": "0.0.0.0",
"HostPort": "27018"
}
]
},
"SandboxKey": "/var/run/docker/netns/80b5cd3f3b8c",
"SecondaryIPAddresses": null,
"SecondaryIPv6Addresses": null,
"EndpointID": "",
"Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"IPAddress": "",
"IPPrefixLen": 0,
"IPv6Gateway": "",
"MacAddress": "",
"Networks": {
"root_default": {
"IPAMConfig": null,
"Links": null,
"Aliases": [
"mongo",
"8f9a6d2c36a1"
],
"NetworkID": "d6b6cc90deda1a99ae078573468d434f589225a578f12a1cd867e969054ad09d",
"EndpointID": "ffac6eccb9cad4692030f0b2649b5be032ed9e0003f22628fb498d5592ce6add",
"Gateway": "172.18.0.1",
"IPAddress": "172.18.0.21",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"MacAddress": "02:42:ac:12:00:15",
"DriverOpts": null
}
}
}
}
]
I don't see the mistake in the configuration. Why is there a connection error?
If you try to access your mongodb instance from a container started within the same docker-compose.yml it's still port 27017 with your setup.
To use port 27018 you should add
command: --port 27018
to the mongo service definition.
Then the published ports will be '27018:27018'. However, if you don't need to access mongodb from outside (mongosh or UI), you can leave out published ports at all. You might even keep 27017 internally then.