I have Dockerfile that I have used many times without an issue. Now I need to add some packages to it (ssmtp and sendmail) and when I add them the build fails with:
Sending build context to Docker daemon 645.3 MB
Sending build context to Docker daemon
Step 0 : FROM debian:jessie
---> 736e5442e772
Step 1 : MAINTAINER Larry Martell <larry.martell@foo.com>
---> Using cache
---> bd272aa26940
Step 2 : ENV HOME /opt/django/CAPgraph/
---> Using cache
---> 1c540ed91808
Step 3 : RUN echo "deb http://http.debian.net/debian jessie-backports main" >> /etc/apt/sources.list
---> Using cache
---> 8788d48e625d
Step 4 : RUN (apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y build-essential git python python-dev python-setuptools nginx sqlite3 supervisor mysql-server libmysqlclient-dev vim cron unzip software-properties-common python-software-properties openjdk-8-jre xvfb wkhtmltopdf ssmtp sendmail)
---> Running in 8986bca93fdb
Get:1 http://security.debian.org jessie/updates InRelease [63.1 kB]
Get:2 http://security.debian.org jessie/updates/main amd64 Packages [436 kB]
Get:3 http://http.debian.net jessie-backports InRelease [166 kB]
Get:4 http://httpredir.debian.org jessie-updates InRelease [145 kB]
Get:5 http://http.debian.net jessie-backports/main amd64 Packages [1031 kB]
Get:6 http://httpredir.debian.org jessie-updates/main amd64 Packages [17.6 kB]
Ign http://httpredir.debian.org jessie InRelease
Get:7 http://httpredir.debian.org jessie Release.gpg [2373 B]
Get:8 http://httpredir.debian.org jessie Release [148 kB]
Get:9 http://httpredir.debian.org jessie/main amd64 Packages [9049 kB]
Fetched 11.1 MB in 9s (1211 kB/s)
Reading package lists...
Reading package lists...
Building dependency tree...
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
sendmail : Depends: sendmail-bin but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
The command '/bin/sh -c (apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y build-essential git python python-dev python-setuptools nginx sqlite3 supervisor mysql-server libmysqlclient-dev vim cron unzip software-properties-common python-software-properties openjdk-8-jre xvfb wkhtmltopdf ssmtp sendmail)' returned a non-zero code: 100
If I add those packages to the list I then complains about others. What does this 'held broken packages' message mean and how do I fix it?
Here is the first part of my Dockerfile:
FROM debian:jessie ENV HOME /opt/django/CAPgraph/
RUN echo "deb http://http.debian.net/debian jessie-backports main" >> /etc/apt/sources.list
RUN (apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y build-essential git python python-dev python-setuptools nginx sqlite3 supervisor mysql-server libmysqlclient-dev vim cron unzip software-properties-common python-software-properties openjdk-8-jre xvfb wkhtmltopdf sendmail ssmtp)
I tried adding sendmail-bin and then it failed with:
The following packages have unmet dependencies:
sendmail-bin : Conflicts: mail-transport-agent
ssmtp : Conflicts: mail-transport-agent
E: Unable to correct problems, you have held broken packages.
I then added mail-transport-agent and it failed with:
Package mail-transport-agent is a virtual package provided by:
opensmtpd 5.7.3p2-1~bpo8+1
ssmtp 2.64-8
sendmail-bin 8.14.4-8+deb8u1
qmail-run 2.0.2+nmu1
postfix 2.11.3-1
nullmailer 1:1.13-1+deb8u1
msmtp-mta 1.4.32-2
masqmail 0.2.30-1
lsb-invalid-mta 4.1+Debian13+nmu1
exim4-daemon-light 4.84.2-2+deb8u3
exim4-daemon-heavy 4.84.2-2+deb8u3
esmtp-run 1.2-12
dma 0.9-1
courier-mta 0.73.1-1.6
citadel-mta 8.24-1+b3
E: Package 'mail-transport-agent' has no installation candidate
Debian is setup to only allow one mail transport agent, and your install command is trying to include two, ssmtp and sendmail/sendmail-bin. Since they conflict with each other, you'll need to remove one of these from your install command.