ERROR: unsatisfiable constraints using apk in dockerfile : <p>I'm trying to install postgis into a postgres container.
Dockerfile:</p>

<pre><code>FROM postgres:9.6.4-alpine

RUN apk update \
    &amp;&amp; apk add -u postgresql-9.6-postgis-2.4 postgresql-9.6-postgis-2.4-scripts \
    &amp;&amp; rm -rf /var/lib/apt/lists/*

COPY ./scripts/postgis.sh  /docker-entrypoint-initdb.d/postgis.sh
</code></pre>

<p>postgis.sh:</p>

<pre><code>#!/bin/sh

for DB in $(psql -t -c  "SELECT datname from pg_database where datname = 'backend'"); do
    echo "Loading PostGIS extensions into $DB"
    "${psql[@]}" --dbname="$DB" &lt;&lt;-'EOSQL'
        CREATE EXTENSION IF NOT EXISTS postgis;
EOSQL
done
</code></pre>

<p>I got this error:</p>

<blockquote>
  <p>ERROR: unsatisfiable constraints:
    postgresql-9.6-postgis-2.4 (missing):
      required by:
                   world[postgresql-9.6-postgis-2.4]
    postgresql-9.6-postgis-2.4-scripts (missing):
      required by:
                   world[postgresql-9.6-postgis-2.4-scripts]
  The command '/bin/sh -c apk update     &amp;&amp; apk add -u postgresql-9.6-postgis-2.4 postgresql-9.6-postgis-2.4-scripts     &amp;&amp; rm -rf /var/lib/apt/lists/*' returned a non-zero code: 2</p>
</blockquote>

<p>I found similar questions such as :</p>

<ol>
<li><a href="https://stackoverflow.com/questions/48417891/error-unsatisfiable-constraints-while-installing-package-in-alpine">ERROR: unsatisfiable constraints: while installing package in alpine
</a></li>
<li><a href="https://stackoverflow.com/questions/36530620/error-unsatisfiable-constraints-on-php7-fpm-alpine">ERROR: unsatisfiable constraints - on php:7-fpm-alpine</a></li>
</ol>

<p>But it doesn't solve my problem.How can I add postgis extension to my postgres container with apk?</p>
