seq-input-gelf
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Published
20 hours ago •
datalust
datalust
Issue with container not setting up UDP
I'm trying to debug what looks to be a weird behaviour when using seq-input-gelf in a container.
Spinning it up via docker/docker compose works fine and I can immediately validate it works as expected:
$ docker run --rm -it -p 12201:12201/udp -e SEQ_ADDRESS=http://logs.lan -e GELF_ENABLE_DIAGNOSTICS="True" datalust/seq-input-gelf
{"@t":"2025-10-23T21:10:51.468743919Z","@l":"DEBUG","@mt":"Starting GELF server"}
{"@t":"2025-10-23T21:10:51.470710742Z","@l":"DEBUG","@mt":"Setting up for UDP"}
{"@t":"2025-10-23T21:11:51.470578468Z","@l":"DEBUG","@mt":"Collected GELF server metrics","process":{"msg":129},"receive":{"chunk":0,"msg_chunked":0,"msg_incomplete_chunk_overflow":0,"msg_unchunked":129},"server":{"process_err":0,"process_ok":129,"receive_err":0,"receive_ok":129,"tcp_conn_accept":0,"tcp_conn_close":0,"tcp_conn_timeout":0,"tcp_msg_overflow":0}}
When managing the container via ansible container module with the same inputs, the container gets created but I never see the Setting up for UDP log line, and I'm unable to successfully send logs to the UDP listener:
$ docker logs -f seq-input-gelf
{"@t":"2025-10-23T20:58:37.469790459Z","@l":"DEBUG","@mt":"Starting GELF server"}
{"@t":"2025-10-23T20:59:37.470057625Z","@l":"DEBUG","@mt":"Collected GELF server metrics","process":{"msg":0},"receive":{"chunk":0,"msg_chunked":0,"msg_incomplete_chunk_overflow":0,"msg_unchunked":0},"server":{"process_err":0,"process_ok":0,"receive_err":0,"receive_ok":0,"tcp_conn_accept":0,"tcp_conn_close":0,"tcp_conn_timeout":0,"tcp_msg_overflow":0}}
The inputs are the same, for reference this is the ansible config block:
- name: foo
docker_container:
name: seq-input-gelf
state: started
image: datalust/seq-input-gelf
ports:
- "12201:12201/udp"
env:
SEQ_ADDRESS: http://logs.lan
GELF_ENABLE_DIAGNOSTICS: "True"
Doing a diff from the two docker inspect outputs doesn't show great differences:
diff -u ansible.json docker.json
--- ansible.json 2025-10-23 22:58:51.018719410 +0200
+++ docker.json 2025-10-23 23:11:35.350364250 +0200
@@ -1,7 +1,7 @@
[
{
- "Id": "3328751dd6061809c817a41b2e92d2d138ddab97f15f05ee82d4cb053c675acb",
- "Created": "2025-10-23T20:58:37.108640078Z",
+ "Id": "3a26d19335bda0f1893bd284edfc4150aaf9df124246740220a019d7c86411b4",
+ "Created": "2025-10-23T21:10:51.051789422Z",
"Path": "/run.sh",
"Args": [],
"State": {
@@ -11,18 +11,18 @@
"Restarting": false,
"OOMKilled": false,
"Dead": false,
- "Pid": 1691998,
+ "Pid": 1699054,
"ExitCode": 0,
"Error": "",
- "StartedAt": "2025-10-23T20:58:37.185128996Z",
+ "StartedAt": "2025-10-23T21:10:51.117114991Z",
"FinishedAt": "0001-01-01T00:00:00Z"
},
"Image": "sha256:312fb387ed1e7b265519a1f95a7659379ff9634950de09d6ab8de62a607a88d2",
- "ResolvConfPath": "/var/lib/docker/containers/3328751dd6061809c817a41b2e92d2d138ddab97f15f05ee82d4cb053c675acb/resolv.conf",
- "HostnamePath": "/var/lib/docker/containers/3328751dd6061809c817a41b2e92d2d138ddab97f15f05ee82d4cb053c675acb/hostname",
- "HostsPath": "/var/lib/docker/containers/3328751dd6061809c817a41b2e92d2d138ddab97f15f05ee82d4cb053c675acb/hosts",
+ "ResolvConfPath": "/var/lib/docker/containers/3a26d19335bda0f1893bd284edfc4150aaf9df124246740220a019d7c86411b4/resolv.conf",
+ "HostnamePath": "/var/lib/docker/containers/3a26d19335bda0f1893bd284edfc4150aaf9df124246740220a019d7c86411b4/hostname",
+ "HostsPath": "/var/lib/docker/containers/3a26d19335bda0f1893bd284edfc4150aaf9df124246740220a019d7c86411b4/hosts",
"LogPath": "",
- "Name": "/seq-input-gelf",
+ "Name": "/thirsty_chandrasekhar",
"RestartCount": 0,
"Driver": "overlay2",
"Platform": "linux",
@@ -43,28 +43,28 @@
"PortBindings": {
"12201/udp": [
{
- "HostIp": "0.0.0.0",
+ "HostIp": "",
"HostPort": "12201"
}
]
},
"RestartPolicy": {
- "Name": "unless-stopped",
+ "Name": "no",
"MaximumRetryCount": 0
},
- "AutoRemove": false,
+ "AutoRemove": true,
"VolumeDriver": "",
"VolumesFrom": null,
"ConsoleSize": [
- 0,
- 0
+ 48,
+ 98
],
"CapAdd": null,
"CapDrop": null,
"CgroupnsMode": "private",
- "Dns": null,
- "DnsOptions": null,
- "DnsSearch": null,
+ "Dns": [],
+ "DnsOptions": [],
+ "DnsSearch": [],
"ExtraHosts": null,
"GroupAdd": null,
"IpcMode": "private",
@@ -86,18 +86,18 @@
"NanoCpus": 0,
"CgroupParent": "",
"BlkioWeight": 0,
- "BlkioWeightDevice": null,
- "BlkioDeviceReadBps": null,
- "BlkioDeviceWriteBps": null,
- "BlkioDeviceReadIOps": null,
- "BlkioDeviceWriteIOps": null,
+ "BlkioWeightDevice": [],
+ "BlkioDeviceReadBps": [],
+ "BlkioDeviceWriteBps": [],
+ "BlkioDeviceReadIOps": [],
+ "BlkioDeviceWriteIOps": [],
"CpuPeriod": 0,
"CpuQuota": 0,
"CpuRealtimePeriod": 0,
"CpuRealtimeRuntime": 0,
"CpusetCpus": "",
"CpusetMems": "",
- "Devices": null,
+ "Devices": [],
"DeviceCgroupRules": null,
"DeviceRequests": null,
"MemoryReservation": 0,
@@ -105,7 +105,7 @@
"MemorySwappiness": null,
"OomKillDisable": null,
"PidsLimit": null,
- "Ulimits": null,
+ "Ulimits": [],
"CpuCount": 0,
"CpuPercent": 0,
"IOMaximumIOps": 0,
@@ -138,32 +138,32 @@
},
"GraphDriver": {
"Data": {
- "ID": "3328751dd6061809c817a41b2e92d2d138ddab97f15f05ee82d4cb053c675acb",
- "LowerDir": "/var/lib/docker/overlay2/0a9ad1c97b35fe5ebb49099b514012894a381f185b1f05dcf115fe66ca5becb5-init/diff:/var/lib/docker/overlay2/67d2f63947d0c756829b377ebc7d4d3602f651c646d7f915a49a0724d4b1d4a5/diff:/var/lib/docker/overlay2/eb8be16255ac6f546362543289d885471ef68fba46d0c38dd0ad3f0ecf2a94c7/diff:/var/lib/docker/overlay2/60b24f76501c9204385a7feac1fb813fdef565c3f206d09790dbdc837a5e58fe/diff:/var/lib/docker/overlay2/8e23f0f13ddb8a14936721c613934952af2e38b0edecb2433d5fffb4c4078981/diff:/var/lib/docker/overlay2/961789e0702ad1580a8e0e525202f179e3186c5098c0c248a4a057c9dbf3e64b/diff",
- "MergedDir": "/var/lib/docker/overlay2/0a9ad1c97b35fe5ebb49099b514012894a381f185b1f05dcf115fe66ca5becb5/merged",
- "UpperDir": "/var/lib/docker/overlay2/0a9ad1c97b35fe5ebb49099b514012894a381f185b1f05dcf115fe66ca5becb5/diff",
- "WorkDir": "/var/lib/docker/overlay2/0a9ad1c97b35fe5ebb49099b514012894a381f185b1f05dcf115fe66ca5becb5/work"
+ "ID": "3a26d19335bda0f1893bd284edfc4150aaf9df124246740220a019d7c86411b4",
+ "LowerDir": "/var/lib/docker/overlay2/012037ed61eab24a410451fa3413142c6545c8961eb15f60d9fa239edf5e1ccb-init/diff:/var/lib/docker/overlay2/67d2f63947d0c756829b377ebc7d4d3602f651c646d7f915a49a0724d4b1d4a5/diff:/var/lib/docker/overlay2/eb8be16255ac6f546362543289d885471ef68fba46d0c38dd0ad3f0ecf2a94c7/diff:/var/lib/docker/overlay2/60b24f76501c9204385a7feac1fb813fdef565c3f206d09790dbdc837a5e58fe/diff:/var/lib/docker/overlay2/8e23f0f13ddb8a14936721c613934952af2e38b0edecb2433d5fffb4c4078981/diff:/var/lib/docker/overlay2/961789e0702ad1580a8e0e525202f179e3186c5098c0c248a4a057c9dbf3e64b/diff",
+ "MergedDir": "/var/lib/docker/overlay2/012037ed61eab24a410451fa3413142c6545c8961eb15f60d9fa239edf5e1ccb/merged",
+ "UpperDir": "/var/lib/docker/overlay2/012037ed61eab24a410451fa3413142c6545c8961eb15f60d9fa239edf5e1ccb/diff",
+ "WorkDir": "/var/lib/docker/overlay2/012037ed61eab24a410451fa3413142c6545c8961eb15f60d9fa239edf5e1ccb/work"
},
"Name": "overlay2"
},
"Mounts": [],
"Config": {
- "Hostname": "3328751dd606",
+ "Hostname": "3a26d19335bd",
"Domainname": "",
"User": "",
- "AttachStdin": false,
+ "AttachStdin": true,
"AttachStdout": true,
"AttachStderr": true,
"ExposedPorts": {
"12201/tcp": {},
"12201/udp": {}
},
- "Tty": false,
- "OpenStdin": false,
- "StdinOnce": false,
+ "Tty": true,
+ "OpenStdin": true,
+ "StdinOnce": true,
"Env": [
- "SEQ_ADDRESS=http://logs.lan",
"GELF_ENABLE_DIAGNOSTICS=True",
+ "SEQ_ADDRESS=http://logs.lan",
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
"SEQ_API_KEY=",
"GELF_ADDRESS="
@@ -185,14 +185,18 @@
},
"NetworkSettings": {
"Bridge": "",
- "SandboxID": "7965ff037c488a03196202a4916fd31ce7f6b1b45ee9066b0bc5fbaf56ae1efd",
- "SandboxKey": "/var/run/docker/netns/7965ff037c48",
+ "SandboxID": "4072597687c58c981f565b2b24e664265f63b117f0d1914b39c72b1dee2e6cf7",
+ "SandboxKey": "/var/run/docker/netns/4072597687c5",
"Ports": {
"12201/tcp": null,
"12201/udp": [
{
"HostIp": "0.0.0.0",
"HostPort": "12201"
+ },
+ {
+ "HostIp": "::",
+ "HostPort": "12201"
}
]
},
@@ -201,24 +205,24 @@
"LinkLocalIPv6PrefixLen": 0,
"SecondaryIPAddresses": null,
"SecondaryIPv6Addresses": null,
- "EndpointID": "4f2874cf13959b5d80aeebdec33f14302dfc83ece8044b1ef1f4ced1159e756c",
+ "EndpointID": "6eb5e5e89164261a3dc991d3647c06f81675998fab7ee85ae6c16ebf211a1f85",
"Gateway": "172.17.0.1",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"IPAddress": "172.17.0.3",
"IPPrefixLen": 16,
"IPv6Gateway": "",
- "MacAddress": "c2:8b:8b:7f:cf:72",
+ "MacAddress": "66:6c:ff:e0:b3:40",
"Networks": {
"bridge": {
"IPAMConfig": null,
"Links": null,
"Aliases": null,
- "MacAddress": "c2:8b:8b:7f:cf:72",
+ "MacAddress": "66:6c:ff:e0:b3:40",
"DriverOpts": null,
"GwPriority": 0,
"NetworkID": "0c889d17cc9e412b005914eaa0271b7efd60beba6f4e445cbc370fe89298d208",
- "EndpointID": "4f2874cf13959b5d80aeebdec33f14302dfc83ece8044b1ef1f4ced1159e756c",
+ "EndpointID": "6eb5e5e89164261a3dc991d3647c06f81675998fab7ee85ae6c16ebf211a1f85",
"Gateway": "172.17.0.1",
"IPAddress": "172.17.0.3",
"IPPrefixLen": 16,
What could it be the difference in the docker container config that makes it so the UDP server is not started/set up by the looks?
Thanks!
HI @msaitz! Do you see a different result if you explicitly specify:
GELF_ADDRESS=udp://0.0.0.0:12201
in your Ansible config block?
The issue is most likely either configuration (as above), or a problem with the GELF server being able to bind to 12201. I am not across the functionality provided by Ansible container modules - any type of heightened security/port binding restrictions/limited-privilege functionality there that might prevent binding to a port?
@nblumhardt thanks for the quick response!
Adding that to the ansible config block does not make a difference. I'm not aware of any of these particularities when using the ansible container module, but I'm investigating.