Traefik https not fully secure - docker

Question

I try to configure my server with Traefik using Docker containers. I configured Traefik so it works, I got the dashboard page. The thing is I would like to have my own GitLab server. I pulled GitLab docker image and I created a docker-compose file.
Even if GitLab container takes long time to start, it seems to work. I'm able to see the Gitlab backend from Traefik dashboard.
The problem is when I try to go on Gitlab's address, my browser (Firefox and Chrome) tells me that my page is not fully secure. Here's the exact error:
Connection is not secure. Parts of this page are not secure (such as images)
I can't find out why I'm getting this error, my configuration is really basic.
Here's my Traefik.toml config:
defaultEntryPoints = ["http", "https"]
# Web section is for the dashboard interface
[web]
address = ":8080"
[web.auth.basic]
users = ["admin:$apr1$TF1rGQz9$OdtHJ15PT6LGWObE4tXuK0"]
# entryPoints section configures the addresses that Traefik and the proxied containers can listen on
[entryPoints]
[entryPoints.http]
address = ":80"
[entryPoints.http.redirect]
entryPoint = "https"
[entryPoints.https]
address = ":443"
[entryPoints.https.tls]
# Acme section is for Let's Encrypt configuration
[acme]
email = "email#email.com"
storage = "acme.json"
entryPoint = "https"
onHostRule = true
onDemand = false
[[acme.domains]]
main = "domain.com"
Here's my docker-compose.yml
version: '3.3'
networks:
proxy:
external: true
internal:
external: false
services:
gitlab:
image: gitlab/gitlab-ce
container_name: gitlab
labels:
- traefik.backend=gitlab
- traefik.frontend.rule=Host:git.domain.com
- traefik.docker.network=proxy
- traefik.port=80
networks:
- internal
- proxy
Here's my docker run command for Traefik container:
docker run -d \
-v /var/run/docker.sock:/var/run/docker.sock \
-v $PWD/traefik.toml:/traefik.toml \
-v $PWD/acme.json:/acme.json \
-e TZ="Europe/Paris" \
-p 80:80 \
-p 443:443 \
-l traefik.frontend.rule=Host:monitor.domain.com \
-l traefik.port=8080 \
--network proxy \
--name traefik \
traefik:1.3.6-alpine --docker --logLevel=DEBUG
As you can see it's a very basic configuration, I don't get why I can't get a fully secure GitLab page. In acme.json file I see my main domain "domain.com" and my sub-domain "git.domain.com". So it should be secure.
What am I missing ? :/

Answer 1

I finally found out why GitLab page was insecure. It's because GitLab use avatar profile picture with insecure path as "htttp://picture_address".
If it can help someone with the same issue :)