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@@ -261,6 +261,64 @@ incoming connections on the Docker port (default 4243):
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.. _installmirrors:
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+Docker and local DNS server warnings
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+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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+
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+Systems which are running Ubuntu or an Ubuntu derivative on the desktop will
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+use `127.0.0.1` as the default nameserver in `/etc/resolv.conf`. NetworkManager
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+sets up dnsmasq to use the real DNS servers of the connection and sets up
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+`nameserver 127.0.0.1` in `/etc/resolv.conf`.
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+
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+When starting containers on these desktop machines, users will see a warning:
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+
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+.. code-block:: bash
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+
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+ WARNING: Local (127.0.0.1) DNS resolver found in resolv.conf and containers can't use it. Using default external servers : [8.8.8.8 8.8.4.4]
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+
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+This warning is shown because the containers can't use the local DNS nameserver
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+and Docker will default to using an external nameserver.
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+
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+This can be worked around by specifying a DNS server to be used by the Docker
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+daemon for the containers:
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+
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+.. code-block:: bash
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+
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+ sudo nano /etc/default/docker
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+ ---
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+ # Add:
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+ DOCKER_OPTS="-dns 8.8.8.8"
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+ # 8.8.8.8 could be replaced with a local DNS server, such as 192.168.1.1
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+ # multiple DNS servers can be specified: -dns 8.8.8.8 -dns 192.168.1.1
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+
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+The Docker daemon has to be restarted:
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+
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+.. code-block:: bash
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+
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+ sudo restart docker
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+
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+.. warning:: If you're doing this on a laptop which connects to various networks, make sure to choose a public DNS server.
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+
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+An alternative solution involves disabling dnsmasq in NetworkManager by
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+following these steps:
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+
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+.. code-block:: bash
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+
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+ sudo nano /etc/NetworkManager/NetworkManager.conf
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+ ----
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+ # Change:
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+ dns=dnsmasq
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+ # to
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+ #dns=dnsmasq
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+
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+NetworkManager and Docker need to be restarted afterwards:
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+
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+.. code-block:: bash
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+
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+ sudo restart network-manager
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+ sudo restart docker
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+
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+.. warning:: This might make DNS resolution slower on some networks.
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+
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Mirrors
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^^^^^^^
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Sven Dowideit