How to Extract Logs from DataHub Containers
DataHub containers, datahub GMS (backend server) and datahub frontend (UI server), write log files to the local container filesystem. To extract these logs, you'll need to get them from inside the container where the services are running.
You can do so easily using the Docker CLI if you're deploying with vanilla docker or compose, and kubectl if you're on K8s.
Step 1: Find the id of the container you're interested in
You'll first need to get the id of the container that you'd like to extract logs for. For example, datahub-gms.
Docker & Docker Compose
To do so, you can view all containers that Docker knows about by running the following command:
johnjoyce@Johns-MBP datahub-fork % docker container ls
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
6c4a280bc457 linkedin/datahub-frontend-react "datahub-frontend/bi…" 5 days ago Up 46 hours (healthy) 0.0.0.0:9002->9002/tcp datahub-frontend-react
122a2488ab63 linkedin/datahub-gms "/bin/sh -c /datahub…" 5 days ago Up 5 days (healthy) 0.0.0.0:8080->8080/tcp datahub-gms
7682dcc64afa confluentinc/cp-schema-registry:5.4.0 "/etc/confluent/dock…" 5 days ago Up 5 days 0.0.0.0:8081->8081/tcp schema-registry
3680fcaef3ed confluentinc/cp-kafka:5.4.0 "/etc/confluent/dock…" 5 days ago Up 5 days 0.0.0.0:9092->9092/tcp, 0.0.0.0:29092->29092/tcp broker
9d6730ddd4c4 neo4j:4.0.6 "/sbin/tini -g -- /d…" 5 days ago Up 5 days 0.0.0.0:7474->7474/tcp, 7473/tcp, 0.0.0.0:7687->7687/tcp neo4j
c97edec663af confluentinc/cp-zookeeper:5.4.0 "/etc/confluent/dock…" 5 days ago Up 5 days 2888/tcp, 0.0.0.0:2181->2181/tcp, 3888/tcp zookeeper
150ba161cf26 mysql:8.2 "docker-entrypoint.s…" 5 days ago Up 5 days 0.0.0.0:3306->3306/tcp, 33060/tcp mysql
4b72a3eab73f elasticsearch:7.9.3 "/tini -- /usr/local…" 5 days ago Up 5 days (healthy) 0.0.0.0:9200->9200/tcp, 9300/tcp elasticsearch
In this case, the container id we'd like to note is 122a2488ab63, which corresponds to the datahub-gms service.
Kubernetes & Helm
Find the name of the pod you're interested in using the following command:
kubectl get pods
...
default datahub-frontend-1231ead-6767 1/1 Running 0 42h
default datahub-gms-c578b47cd-7676 1/1 Running 0 13d
...
In this case the pod name we'd like to note is datahub-gms-c578b47cd-7676 , which contains the GMS backend service.
Step 2: Find the log files
The second step is to view all log files. Log files will live inside the container under the following directories for each service:
- datahub-gms:
/tmp/datahub/logs/gms - datahub-frontend:
/tmp/datahub/logs/datahub-frontend
There are 2 types of logs that are collected:
- Info Logs: These include info, warn, error log lines. They are what print to stdout when the container runs.
- Debug Logs: These files have shorter retention (past 1 day) but include more granular debug information from the DataHub code specifically. We ignore debug logs from external libraries that DataHub depends on.
Docker & Docker Compose
Since log files are named based on the current date, you'll need to use "ls" to see which files currently exist. To do so, you can use the docker exec command, using the container id recorded in step one:
docker exec --privileged <container-id> <shell-command>
For example:
johnjoyce@Johns-MBP datahub-fork % docker exec --privileged 122a2488ab63 ls -la /tmp/datahub/logs/gms
total 4664
drwxr-xr-x 2 datahub datahub 4096 Jul 28 05:14 .
drwxr-xr-x 3 datahub datahub 4096 Jul 23 08:37 ..
-rw-r--r-- 1 datahub datahub 2001112 Jul 23 23:33 gms.2021-23-07-0.log
-rw-r--r-- 1 datahub datahub 74343 Jul 24 20:29 gms.2021-24-07-0.log
-rw-r--r-- 1 datahub datahub 70252 Jul 25 17:56 gms.2021-25-07-0.log
-rw-r--r-- 1 datahub datahub 626985 Jul 26 23:36 gms.2021-26-07-0.log
-rw-r--r-- 1 datahub datahub 712270 Jul 27 23:59 gms.2021-27-07-0.log
-rw-r--r-- 1 datahub datahub 867707 Jul 27 23:59 gms.debug.2021-27-07-0.log
-rw-r--r-- 1 datahub datahub 3563 Jul 28 05:26 gms.debug.log
-rw-r--r-- 1 datahub datahub 382443 Jul 28 16:16 gms.log
Depending on your issue, you may be interested to view both debug and normal info logs.
Kubernetes & Helm
Since log files are named based on the current date, you'll need to use "ls" to see which files currently exist. To do so, you can use the kubectl exec command, using the pod name recorded in step one:
kubectl exec datahub-frontend-1231ead-6767 -n default -- ls -la /tmp/datahub/logs/gms
total 36388
drwxr-xr-x 2 datahub datahub 4096 Jul 29 07:45 .
drwxr-xr-x 3 datahub datahub 17 Jul 15 08:47 ..
-rw-r--r-- 1 datahub datahub 104548 Jul 15 22:24 gms.2021-15-07-0.log
-rw-r--r-- 1 datahub datahub 12684 Jul 16 14:55 gms.2021-16-07-0.log
-rw-r--r-- 1 datahub datahub 2482571 Jul 17 14:40 gms.2021-17-07-0.log
-rw-r--r-- 1 datahub datahub 49120 Jul 18 14:31 gms.2021-18-07-0.log
-rw-r--r-- 1 datahub datahub 14167 Jul 19 23:47 gms.2021-19-07-0.log
-rw-r--r-- 1 datahub datahub 13255 Jul 20 22:22 gms.2021-20-07-0.log
-rw-r--r-- 1 datahub datahub 668485 Jul 21 19:52 gms.2021-21-07-0.log
-rw-r--r-- 1 datahub datahub 1448589 Jul 22 20:18 gms.2021-22-07-0.log
-rw-r--r-- 1 datahub datahub 44187 Jul 23 13:51 gms.2021-23-07-0.log
-rw-r--r-- 1 datahub datahub 14173 Jul 24 22:59 gms.2021-24-07-0.log
-rw-r--r-- 1 datahub datahub 13263 Jul 25 21:11 gms.2021-25-07-0.log
-rw-r--r-- 1 datahub datahub 13261 Jul 26 19:02 gms.2021-26-07-0.log
-rw-r--r-- 1 datahub datahub 1118105 Jul 27 21:10 gms.2021-27-07-0.log
-rw-r--r-- 1 datahub datahub 678423 Jul 28 23:57 gms.2021-28-07-0.log
-rw-r--r-- 1 datahub datahub 1776274 Jul 28 07:19 gms.debug.2021-28-07-0.log
-rw-r--r-- 1 datahub datahub 27576533 Jul 29 09:55 gms.debug.log
-rw-r--r-- 1 datahub datahub 1195940 Jul 29 14:54 gms.log
In the next step, we'll save specific log files to our local filesystem.
Step 3: Save Container Log File to Local
This step involves saving a copy of the container log files to your local filesystem for further investigation.
Docker & Docker Compose
Simply use the docker exec command to "cat" the log file(s) of interest and route them to a new file.
docker exec --privileged 122a2488ab63 cat /tmp/datahub/logs/gms/gms.debug.log > my-local-log-file.log
Now you should be able to view the logs locally.
Kubernetes & Helm
There are a few ways to get files out of the pod and into a local file. You can either use kubectl cp or simply cat and pipe the file of interest. We'll show an example using the latter approach:
kubectl exec datahub-frontend-1231ead-6767 -n default -- cat /tmp/datahub/logs/gms/gms.log > my-local-gms.log