diff --git a/dockerfiles/swh-deposit/Dockerfile b/dockerfiles/swh-deposit/Dockerfile
index 60837ff..d280ca4 100644
--- a/dockerfiles/swh-deposit/Dockerfile
+++ b/dockerfiles/swh-deposit/Dockerfile
@@ -1,16 +1,16 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && apt-get upgrade -y && \
   apt-get install -y libsystemd-dev postgresql-client && \
   apt-get clean && \
   rm -rf /var/lib/apt/lists/*
 
 RUN pip install swh-deposit gunicorn
 RUN pip install psycopg2-binary  # to make pip silent
 COPY server.yml /etc/softwareheritage/deposit/
 COPY private.yml /etc/softwareheritage/deposit/
 
 COPY entrypoint.sh /
 EXPOSE 5006
 ENTRYPOINT ["/entrypoint.sh"]
diff --git a/dockerfiles/swh-indexer-journal-client/Dockerfile b/dockerfiles/swh-indexer-journal-client/Dockerfile
index 8f8d9a4..d57fbd0 100644
--- a/dockerfiles/swh-indexer-journal-client/Dockerfile
+++ b/dockerfiles/swh-indexer-journal-client/Dockerfile
@@ -1,12 +1,12 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y libsystemd-dev
 
 RUN pip install swh-indexer
 COPY journal_client.yml /etc/softwareheritage/indexer/
 COPY entrypoint.sh /
 
 ENTRYPOINT ["/entrypoint.sh"]
 
diff --git a/dockerfiles/swh-indexer-storage/Dockerfile b/dockerfiles/swh-indexer-storage/Dockerfile
index df54a38..026ed88 100644
--- a/dockerfiles/swh-indexer-storage/Dockerfile
+++ b/dockerfiles/swh-indexer-storage/Dockerfile
@@ -1,14 +1,14 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y \
     libsystemd-dev postgresql-client
 
 RUN pip install swh-indexer
 COPY indexer_storage.yml /
 COPY entrypoint.sh /
 
 ENTRYPOINT ["/entrypoint.sh"]
 
 EXPOSE 5002
diff --git a/dockerfiles/swh-indexer-worker/Dockerfile b/dockerfiles/swh-indexer-worker/Dockerfile
index 9301025..254f725 100644
--- a/dockerfiles/swh-indexer-worker/Dockerfile
+++ b/dockerfiles/swh-indexer-worker/Dockerfile
@@ -1,20 +1,20 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y \
     libsystemd-dev postgresql-client
 
 RUN pip install swh-indexer
 RUN useradd -ms /bin/bash swh
 COPY entrypoint.sh /
 
 COPY mimetype.yml /home/swh/.config/swh/indexer/
 COPY fossology_license.yml /home/swh/.config/swh/indexer/
 COPY origin_head.yml /home/swh/.config/swh/indexer/
 COPY revision_metadata.yml /home/swh/.config/swh/indexer/
 COPY origin_intrinsic_metadata.yml /home/swh/.config/swh/indexer/
 RUN chown -R swh: /home/swh/.config/
 
 USER swh
 ENTRYPOINT ["/entrypoint.sh"]
diff --git a/dockerfiles/swh-journal-client/Dockerfile b/dockerfiles/swh-journal-client/Dockerfile
index b614527..36f4f75 100644
--- a/dockerfiles/swh-journal-client/Dockerfile
+++ b/dockerfiles/swh-journal-client/Dockerfile
@@ -1,12 +1,12 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y libsystemd-dev
 
 RUN pip install swh-journal
 COPY logger.yml /etc/softwareheritage/journal/
 COPY client.py /
 COPY entrypoint.sh /
 
 ENTRYPOINT ["/entrypoint.sh"]
diff --git a/dockerfiles/swh-journal-publisher/Dockerfile b/dockerfiles/swh-journal-publisher/Dockerfile
index 9409540..c16f97e 100644
--- a/dockerfiles/swh-journal-publisher/Dockerfile
+++ b/dockerfiles/swh-journal-publisher/Dockerfile
@@ -1,11 +1,11 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y libsystemd-dev
 
 RUN pip install swh-journal
 COPY publisher.yml /etc/softwareheritage/journal/
 COPY entrypoint.sh /
 
 ENTRYPOINT ["/entrypoint.sh"]
diff --git a/dockerfiles/swh-listers-worker/Dockerfile b/dockerfiles/swh-listers-worker/Dockerfile
index 2cfacbf..06d04f7 100644
--- a/dockerfiles/swh-listers-worker/Dockerfile
+++ b/dockerfiles/swh-listers-worker/Dockerfile
@@ -1,16 +1,16 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y \
     libsystemd-dev postgresql-client
 
 RUN pip install swh-lister
 RUN useradd -ms /bin/bash swh
 COPY entrypoint.sh /
 
 COPY lister.yml /home/swh/.config/swh/
 RUN chown -R swh: /home/swh/.config/
 
 USER swh
 ENTRYPOINT ["/entrypoint.sh"]
diff --git a/dockerfiles/swh-loaders-worker/Dockerfile b/dockerfiles/swh-loaders-worker/Dockerfile
index 1c8a450..6580088 100644
--- a/dockerfiles/swh-loaders-worker/Dockerfile
+++ b/dockerfiles/swh-loaders-worker/Dockerfile
@@ -1,25 +1,25 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y \
     libsystemd-dev libapr1-dev libaprutil1-dev libsvn-dev
 
 RUN pip install \
         swh-loader-debian \
         swh-loader-dir \
         swh-loader-git \
         swh-loader-mercurial \
         swh-loader-pypi \
         swh-loader-svn \
         swh-loader-tar
 
 
 RUN useradd -ms /bin/bash swh
 COPY entrypoint.sh /
 
 COPY loader.yml /home/swh/.config/swh/
 RUN chown -R swh: /home/swh/.config/
 
 USER swh
 ENTRYPOINT ["/entrypoint.sh"]
diff --git a/dockerfiles/swh-objstorage/Dockerfile b/dockerfiles/swh-objstorage/Dockerfile
index 8f84487..3fc22e4 100644
--- a/dockerfiles/swh-objstorage/Dockerfile
+++ b/dockerfiles/swh-objstorage/Dockerfile
@@ -1,16 +1,16 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y \
     libsystemd-dev
 
 RUN pip install swh-objstorage
 COPY objstorage.yml /
 COPY entrypoint.sh /
 
 RUN mkdir -p /srv/softwareheritage/objects
 
 ENTRYPOINT ["/entrypoint.sh"]
 
 EXPOSE 5003
diff --git a/dockerfiles/swh-scheduler-api/Dockerfile b/dockerfiles/swh-scheduler-api/Dockerfile
index 0369f1b..95be8ac 100644
--- a/dockerfiles/swh-scheduler-api/Dockerfile
+++ b/dockerfiles/swh-scheduler-api/Dockerfile
@@ -1,14 +1,14 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y \
     libsystemd-dev postgresql-client
 
 RUN pip install swh-scheduler
 COPY scheduler.yml /
 COPY entrypoint.sh /
 
 ENTRYPOINT ["/entrypoint.sh"]
 
 EXPOSE 5008
diff --git a/dockerfiles/swh-scheduler-worker/Dockerfile b/dockerfiles/swh-scheduler-worker/Dockerfile
index b0c4aa9..c964c6c 100644
--- a/dockerfiles/swh-scheduler-worker/Dockerfile
+++ b/dockerfiles/swh-scheduler-worker/Dockerfile
@@ -1,16 +1,16 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y \
     libsystemd-dev postgresql-client libpq-dev
 
 RUN pip install swh-scheduler --no-binary psycopg2
 RUN mkdir -p /etc/softwareheritage/worker/
 COPY scheduler.yml /etc/softwareheritage/
 # XXX this should NOT be needed.
 # Some cleanup work in config files handling seems necessary...
 RUN ln -s /etc/softwareheritage/scheduler.yml /etc/softwareheritage/worker/
 COPY entrypoint.sh /
 
 ENTRYPOINT ["/entrypoint.sh"]
diff --git a/dockerfiles/swh-storage-listener/Dockerfile b/dockerfiles/swh-storage-listener/Dockerfile
index 93548a1..b70c36e 100644
--- a/dockerfiles/swh-storage-listener/Dockerfile
+++ b/dockerfiles/swh-storage-listener/Dockerfile
@@ -1,12 +1,12 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y \
     libsystemd-dev postgresql-client
 
 RUN pip install swh-storage kafka_python
 COPY listener.yml /etc/softwareheritage/storage/
 COPY entrypoint.sh /
 
 ENTRYPOINT ["/entrypoint.sh"]
diff --git a/dockerfiles/swh-storage/Dockerfile b/dockerfiles/swh-storage/Dockerfile
index f06f94b..f4d4878 100644
--- a/dockerfiles/swh-storage/Dockerfile
+++ b/dockerfiles/swh-storage/Dockerfile
@@ -1,14 +1,14 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && \
   apt-get install -y \
     libsystemd-dev postgresql-client
 
 RUN pip install swh-storage
 COPY storage.yml /
 COPY entrypoint.sh /
 
 ENTRYPOINT ["/entrypoint.sh"]
 
 EXPOSE 5002
diff --git a/dockerfiles/swh-web/Dockerfile b/dockerfiles/swh-web/Dockerfile
index cc0e42f..1235d5d 100644
--- a/dockerfiles/swh-web/Dockerfile
+++ b/dockerfiles/swh-web/Dockerfile
@@ -1,18 +1,18 @@
-FROM python:3
+FROM python:3.6
 
 RUN export DEBIAN_FRONTEND=noninteractive && \
   apt-get update && apt-get upgrade -y && \
   apt-get install -y libsystemd-dev && \
   apt-get clean && \
   rm -rf /var/lib/apt/lists/*
 
 RUN pip install swh-web
 RUN pip install psycopg2-binary  # to make pip silent
 RUN python3 -m swh.web.manage migrate
 
 COPY web.yml /etc/softwareheritage/web/
 COPY entrypoint.sh /
 
 ENTRYPOINT ["/entrypoint.sh"]
 
 EXPOSE 5004