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< li class = "toctree-l1" > < a class = "reference internal" href = "cdist-why.html" > 1. Why should I use cdist?< / a > < / li >
< li class = "toctree-l1" > < a class = "reference internal" href = "cdist-features.html" > 2. Features< / a > < / li >
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< li class = "toctree-l1 current" > < a class = "current reference internal" href = "#" > 18. Messaging< / a > < ul >
< li class = "toctree-l2" > < a class = "reference internal" href = "#description" > 18.1. Description< / a > < / li >
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< li class = "toctree-l1" > < a class = "reference internal" href = "cdist-parallelization.html" > 19. Parallelization< / a > < / li >
< li class = "toctree-l1" > < a class = "reference internal" href = "cdist-inventory.html" > 20. Inventory< / a > < / li >
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< li > 18. Messaging< / li >
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< h1 > 18. Messaging< a class = "headerlink" href = "#messaging" title = "Permalink to this headline" > ¶< / a > < / h1 >
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< h2 > 18.1. Description< a class = "headerlink" href = "#description" title = "Permalink to this headline" > ¶< / a > < / h2 >
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< p > cdist has a simple but powerful way of allowing communication between
the initial manifest and types as well as types and types.< / p >
< p > Whenever execution is passed from cdist to one of the
scripts described below, cdist generate 2 new temporary files
and exports the environment variables < strong > __messages_in< / strong > and
< strong > __messages_out< / strong > to point to them.< / p >
< p > Before handing over the control, the content of the global message
file is copied into the file referenced by < strong > $__messages_in< / strong > .< / p >
< p > After cdist gained control back, the content of the file referenced
by < strong > $__messages_out< / strong > is appended to the global message file.< / p >
< p > This way overwriting any of the two files by accident does not
interfere with other types.< / p >
< p > The order of execution is not defined unless you create dependencies
between the different objects (see < a class = "reference external" href = "cdist-manifest.html" > cdist manifest< / a > ) and thus you
can only react reliably on messages by objects that you depend on.< / p >
< / div >
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< h2 > 18.2. Availability< a class = "headerlink" href = "#availability" title = "Permalink to this headline" > ¶< / a > < / h2 >
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< p > Messaging is possible between all < strong > local< / strong > scripts:< / p >
< ul class = "simple" >
< li > initial manifest< / li >
< li > type/manifest< / li >
< li > type/gencode-local< / li >
< li > type/gencode-remote< / li >
< / ul >
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< div class = "section" id = "examples" >
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< h2 > 18.3. Examples< a class = "headerlink" href = "#examples" title = "Permalink to this headline" > ¶< / a > < / h2 >
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< p > When you want to emit a message use:< / p >
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< div class = "highlight-sh" > < div class = "highlight" > < pre > < span > < / span > < span class = "nb" > echo< / span > < span class = "s2" > " something" < / span > > > < span class = "s2" > " < / span > < span class = "nv" > $__messages_out< / span > < span class = "s2" > " < / span >
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< / pre > < / div >
< / div >
< p > When you want to react on a message use:< / p >
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< div class = "highlight-sh" > < div class = "highlight" > < pre > < span > < / span > < span class = "k" > if< / span > grep -q < span class = "s2" > " ^__your_type/object/id:something" < / span > < span class = "s2" > " < / span > < span class = "nv" > $__messages_in< / span > < span class = "s2" > " < / span > < span class = "p" > ;< / span > < span class = "k" > then< / span >
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< span class = "nb" > echo< / span > < span class = "s2" > " I do something else" < / span >
< span class = "k" > fi< / span >
< / pre > < / div >
< / div >
< p > Some real life examples:< / p >
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< div class = "highlight-sh" > < div class = "highlight" > < pre > < span > < / span > < span class = "c1" > # Reacting on changes from block for keepalive< / span >
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< span class = "k" > if< / span > grep -q < span class = "s2" > " ^__block/keepalive-vrrp" < / span > < span class = "s2" > " < / span > < span class = "nv" > $__messages_in< / span > < span class = "s2" > " < / span > < span class = "p" > ;< / span > < span class = "k" > then< / span >
< span class = "nb" > echo< / span > /etc/init.d/keepalived restart
< span class = "k" > fi< / span >
< span class = "c1" > # Reacting on changes of configuration files< / span >
< span class = "k" > if< / span > grep -q < span class = "s2" > " ^__file/etc/one" < / span > < span class = "nv" > $__messages_in< / span > < span class = "p" > ;< / span > < span class = "k" > then< / span >
< span class = "nb" > echo< / span > < span class = "s1" > ' for init in /etc/init.d/opennebula*; do $init restart; done' < / span >
< span class = "k" > fi< / span >
< / pre > < / div >
< / div >
< p > Restart sshd on changes< / p >
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< div class = "highlight-sh" > < div class = "highlight" > < pre > < span > < / span > < span class = "nv" > os< / span > < span class = "o" > =< / span > < span class = "s2" > " < / span > < span class = "k" > $(< / span > cat < span class = "s2" > " < / span > < span class = "nv" > $__global< / span > < span class = "s2" > /explorer/os" < / span > < span class = "k" > )< / span > < span class = "s2" > " < / span >
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< span class = "k" > case< / span > < span class = "s2" > " < / span > < span class = "nv" > $os< / span > < span class = "s2" > " < / span > in
centos< span class = "p" > |< / span > redhat< span class = "p" > |< / span > suse< span class = "o" > )< / span >
< span class = "nv" > restart< / span > < span class = "o" > =< / span > < span class = "s2" > " /etc/init.d/sshd restart" < / span >
< span class = "p" > ;;< / span >
debian< span class = "p" > |< / span > ubuntu< span class = "o" > )< / span >
< span class = "nv" > restart< / span > < span class = "o" > =< / span > < span class = "s2" > " /etc/init.d/ssh restart" < / span >
< span class = "p" > ;;< / span >
*< span class = "o" > )< / span >
cat < span class = "s" > < < eof > & 2< / span >
< span class = "s" > Unsupported os $os.< / span >
< span class = "s" > If you would like to have this type running on $os,< / span >
< span class = "s" > you can either develop the changes and send a pull< / span >
< span class = "s" > request or ask for a quote at www.ungleich.ch< / span >
< span class = "s" > eof< / span >
< span class = "nb" > exit< / span > < span class = "m" > 1< / span >
< span class = "p" > ;;< / span >
< span class = "k" > esac< / span >
< span class = "k" > if< / span > grep -q < span class = "s2" > " ^__key_value/PermitRootLogin" < / span > < span class = "s2" > " < / span > < span class = "nv" > $__messages_in< / span > < span class = "s2" > " < / span > < span class = "p" > ;< / span > < span class = "k" > then< / span >
< span class = "nb" > echo< / span > < span class = "nv" > $restart< / span >
< span class = "k" > fi< / span >
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